A frequent cause of failure of portable and hand-held devices is an accidental drop to the ground. The effect of electromigration on the mechanical properties of solder joints was discussed in this paper. Without curr...
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A frequent cause of failure of portable and hand-held devices is an accidental drop to the ground. The effect of electromigration on the mechanical properties of solder joints was discussed in this paper. Without current stressing, the samples were broken in the bulk of solder or at the interface of Al interconnect and solder. if the Al-solder interfacial mechanical strength was improved by changed the interfacial structure or optimized the jointing process, the flip chip devices would show the lonely ductile fracture in the bulk of solder. After electromigration the samples were broken abruptly at the interface near the chip side while the bulk of the solder joints maintained the original shape. Due to the interfacial reaction and the polarity effect of electromigration on the interfaces, a ductile solder joint can become a brittle solder joint. The ductile-to-brittle transition is very sensitive to a high speed shear stress applied to the joints. Because solder alloys are ductile by nature, it is of interest to understand how electromigration can influence the mechanical properties of solder joints' interfaces and change their ductile nature. Owing to the polarity effect of electromigration, vacancies will accumulate to form voids at the cathode interface of solder joints. Besides, much more intermetallic compound formation at the joint interfaces also caused the ductile-to-brittle transition. Thus the interfaces become more and more brittle with time due to IMC formation or vacancy accumulation from electromigration.
This paper presents a real-time alga classifier designed for flow-cytometry-based marine alga monitoring *** difficulties of such classification include:1)the shape of the same algae category is deformable,and largely...
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This paper presents a real-time alga classifier designed for flow-cytometry-based marine alga monitoring *** difficulties of such classification include:1)the shape of the same algae category is deformable,and largely variant due to the individual differences and mature stage;2)the image of algae may vary due to different 3D positions to the imaging plane and partial occlusion;3)the images also contain unknown algae and *** the proposed method,several shape features were developed,a naive Bayes classifier(NBC)was trained to reject the contaminative objects and unknown algae,and a support vector machine(SVM)was used to classify the algae to taxonomic *** approach achieved greater 90%accuracy on a collection of algal *** test on contaminated algal image set(containing unknown algae and non-algae objects such as sands)also demonstrated promising results.
The remote sensing based Production Efficiency Models (PEMs), springs from the concept of “Light Use Efficiency” and has been applied more and more in estimating terrestrial Net Primary Productivity (NPP) regionally...
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The remote sensing based Production Efficiency Models (PEMs), springs from the concept of “Light Use Efficiency” and has been applied more and more in estimating terrestrial Net Primary Productivity (NPP) regionally and globally. However, global NPP estimates vary greatly among different models in different data sources and handling methods. Because direct observation or measurement of NPP is unavailable at global scale, the precision and reliability of the models cannot be guaranteed. Though, there are ways to improve the accuracy of the models from input parameters. In this study, five remote sensing based PEMs have been compared: CASA, GLO-PEM, TURC, SDBM and VPM. We divided input parameters into three categories, and analyzed the uncertainty of (1) vegetation distribution, (2) fraction of photosynthetically active radiation absorbed by the canopy (fPAR) and (3) light use efficiency (ε). Ground measurements of Hulunbeier typical grassland and meteorology measurements were introduced for accuracy evaluation. Results show that a real-time, more accurate vegetation distribution could significantly affect the accuracy of the models, since it's applied directly or indirectly in all models and affects other parameters simultaneously. Higher spatial and spectral resolution remote sensing data may reduce uncertainty of fPAR up to 51.3%, which is essential to improve model accuracy.
According to limitations of previous chlorine decay models, a new model named as variable rate coefficient model (VRC) was built to improve the accuracy and reliability of chlorine decay model. The VRC model includes ...
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According to limitations of previous chlorine decay models, a new model named as variable rate coefficient model (VRC) was built to improve the accuracy and reliability of chlorine decay model. The VRC model includes 4 parameters (X0, κ0, kmin and α) and is based on the kinetic rate equations from concurrent bimolecular second-order reactions. In this study, 6 data sets from different water sources were used. Three models including VRC model, the first-order model and a second-order reactive species model built by Boccelli et al. were calibrated and compared. Results show that compared with other two models, the simulated values of VRC model agree very well with the experimental data. The VRC model can accurately predict chlorine decay. In order to ensure the accuracy of VRC model, it is preferable to calibrate the VRC model using data sets with a chlorine concentration that is at least as high as or even higher than that used during normal operating conditions. Furthermore, the chlorine concentrations used as model input should be adjusted to minimize the differences between model predictions and the observed chlorine concentration.
Electromigration in flip-chip bumps of Sn3.0AgO.5Cu, has been studied at current density of 2.03l04 A/cm2• Three, potential failure modes induced by electromigration in SnAgCu, flip-chip bumps were investigated in ter...
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Electromigration in flip-chip bumps of Sn3.0Ag0.5Cu has been studied at current density of 2.03times10 4 A/cm 2 . Three potential failure modes induced by electromigration in SnAgCu flip-chip bumps were investigated ...
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Electromigration in flip-chip bumps of Sn3.0Ag0.5Cu has been studied at current density of 2.03times10 4 A/cm 2 . Three potential failure modes induced by electromigration in SnAgCu flip-chip bumps were investigated in terms of microstructural evolution. According to IPC standard or U.S. Military Standard (MIL-STD), all theses three kinds of damages would be determined failure in failure-analysis procedures for microcircuits.
In order to characterize the interdependence of all the factors directly in the process of bioleaching polymetallic nodules in deep sea, this paper conducted the aerobic and anaerobic leaching experiments of a microbe...
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In order to characterize the interdependence of all the factors directly in the process of bioleaching polymetallic nodules in deep sea, this paper conducted the aerobic and anaerobic leaching experiments of a microbe catalysis MnO2-FeS2-H2SO4 system. The dynamic model of valuable metals by microbe catalysis leaching under anaerobic condition, that is the shrinking core model, was established using the DLVO theory. In the oxidation-reduction process of polymetallic nodules and pyrites, the Mn-leaching mechanics under anaerobic condition was the circulate transformation between Fe2+ and Fe3+ by microbe catalysis. The microbes absorbed on the surface of mineral and accelerated the reaction process, the mineral particles got small continuously during the reaction. The further study on the experiments indicates that retract model curves fit the experimental ones nicely, which verified the reliability of the model.
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